Medical entrepreneurs are remaking the emergency room experience. They're pulling the emergency room out of the hospital and planting it in the strip mall. It's called a "free-standing ER," and some 400 of them have opened across the country in the past four years. The trend is hot around Houston, where there are already 41 free-standing ERs and 10 more in the works. "I think these emergency medical centers are springing up like Texas wildflowers in the springtime," says Vivian Ho, a health economist at Rice University in Houston. "It's really amazing."